clang/test/CodeGenCXX/OmitRTTIComponentABI/vbase-offset.cpp

   1 /// Check that the offset to top calculation is adjusted to account for the
   2 /// omitted RTTI entry.
   3
   4 // RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fexperimental-omit-vtable-rtti -fno-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=POINTER %s
   5 // RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fexperimental-relative-c++-abi-vtables -fexperimental-omit-vtable-rtti -fno-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=RELATIVE %s
   6
   7 /// Some important things to check:
   8 /// - The n16 here represents the virtual thunk size. Normally this would be 24
   9 ///   to represent 3 components (offset to top, RTTI component, vcall offset),
  10 ///   but since one 8-byte component is removed, this is now 16.
  11 // POINTER-LABEL: @_ZTv0_n16_N7Derived1fEi(
  12 // POINTER-NEXT:  entry:
  13 // POINTER:        [[vtable:%.+]] = load ptr, ptr %this1, align 8
  14
  15 /// Same here - When getting the vbase offset, we subtract 2 pointer sizes
  16 /// instead of 3.
  17 // POINTER-NEXT:   [[vbase_offset_ptr:%.+]] = getelementptr inbounds i8, ptr [[vtable]], i64 -16
  18 // POINTER-NEXT:   [[vbase_offset:%.+]] = load i64, ptr [[vbase_offset_ptr]], align 8
  19 // POINTER-NEXT:   [[adj_this:%.+]] = getelementptr inbounds i8, ptr %this1, i64 [[vbase_offset]]
  20 // POINTER:   [[call:%.+]] = tail call noundef i32 @_ZN7Derived1fEi(ptr noundef{{[^,]*}} [[adj_this]], i32 noundef {{.*}})
  21 // POINTER:   ret i32 [[call]]
  22
  23 /// For relative vtables, it's almost the same except the offset sizes are
  24 /// halved.
  25 // RELATIVE-LABEL: @_ZTv0_n8_N7Derived1fEi(
  26 // RELATIVE-NEXT:  entry:
  27 // RELATIVE:        [[vtable:%.+]] = load ptr, ptr %this1, align 8
  28 // RELATIVE-NEXT:   [[vbase_offset_ptr:%.+]] = getelementptr inbounds i8, ptr [[vtable]], i64 -8
  29 // RELATIVE-NEXT:   [[vbase_offset:%.+]] = load i32, ptr [[vbase_offset_ptr]], align 4
  30 // RELATIVE-NEXT:   [[adj_this:%.+]] = getelementptr inbounds i8, ptr %this1, i32 [[vbase_offset]]
  31 // RELATIVE:        [[call:%.+]] = tail call noundef i32 @_ZN7Derived1fEi(ptr noundef{{[^,]*}} [[adj_this]], i32 noundef {{.*}})
  32 // RELATIVE:        ret i32 [[call]]
  33
  34 class Base {
  35 public:
  36   virtual int f(int x);
  37
  38 private:
  39   long x;
  40 };
  41
  42 class Derived : public virtual Base {
  43 public:
  44   virtual int f(int x);
  45
  46 private:
  47   long y;
  48 };
  49
  50 int Base::f(int x) { return x + 1; }
  51 int Derived::f(int x) { return x + 2; }